A beleaguered woman arrives at the industrial-cleansers store where she has asked the owner to look after her son. It's past closing time. She has been through hell. A ponytailed man with one arm answers the door and frowns.

Is he annoyed at being made to stay late? A short-tempered babysitter? Does he think he's being manipulated by a beautiful woman? Clifton Collins Jr., who plays the store owner, Winston (opposite Amy Adams' Rose), in "Sunshine Cleaning," reveled in the character's mysteries and the freedom to fill in blanks.

"The script said, 'There's a room full of model planes.' Why? How did I lose my arm? I'm one of the smaller characters, so there weren't many answers," said the 38-year-old actor.

In the film, Rose and her sister meet Winston when the novices start a business cleaning crime scenes. Collins diligently researched amputees and the chemicals and devices Winston sells. But apart from such tangible details, his interpretation was rooted in his personal journey away from, and back to, his own name.

Collins' grandfather was the Mexican American comic actor Pedro Gonzalez Gonzalez, best known for appearing opposite John Wayne in such films as "Rio Bravo" and "The High and the Mighty." Collins speaks bitterly of people who've written critically of his grandfather's screen image, one of whom called Gonzalez a "Tio Tom" for his supposedly fake accent. "I sat down with [that author] and told him, 'You know, that's my grandfather's accent. That's how he speaks,' " he said. "This was a Mexican American in the '50s who couldn't read and who became a contract player. I know how hard it is to get a job . . . . So for people to be writing these books, it was just infuriating to me."

Collins' relationship with his father, however, was less inspiring. His parents divorced when he was a toddler. "He was never really there for me as a dad. He was like one of those flaky friends you have. He was fun to be around, but my grandfather was the main reason I didn't go to prison like my friends, and why I got into acting," Collins said. So the young actor started billing himself as Clifton Gonzalez Gonzalez.

Pedro Gonzalez Gonzalez died in 2006 at age 80 but had the last laugh on his detractors: Due to campaigning by Collins and friends such as Samuel L. Jackson, he received a star on the Hollywood Walk of Fame last year.

Collins switched back to his birth name in 1999, in large part because he was "haunted" by his father's death in 1997. "I lost him to a suicide when I was doing 'One Eight Seven' with Sam Jackson. I always felt bad about it, but on the same note . . . me and my sister would spend weekends at my grandparents', waiting for my dad, who lived, like, seven miles away in Inglewood, to pick us up. We'd be there on time at 9, and I'd wait until 10, 11, 12, until my grandmother would be like, 'Hey, mijo, let's go play.' 'I'm waiting for my daddy.' 'Mijo, your dad's probably not going to come.' "

So in "Sunshine Cleaning," Collins put a personal spin on that scene when Rose comes to retrieve her son.

"It's when you're growing fond of someone and you find out some ugly things, like, in my opinion at that time, abandoning your child. I didn't know when she was going to come back," he said of his character. But as Winston, he does hear her out.

"How can you not listen to a beautiful woman who's in tears? Real tears, not fake tears. And my personal connection to this child, which is part of my own issues. . . . It wasn't written that way, but I'm thinking, this kid is sleeping on my couch and his mom was supposed to be here for him a long time ago. That's not cool for any kid. So I proposed that I would be a little upset with her.